Circuit interrupter



April 18, 1939. J. M sANDiN rncUIT INTERRUPTER' Filed Sept. l2, 1935 5Sheets-Sheet l l N VEN TOR //ome M50/vdi?.

ATTO R N E v 4WITNESSES: I PZ/Q.

April 18, 1939. v J, M SANDIN 2,154,703

cIRcUl'T INTERRUPTER Filed Sept. 1 2, 1935 '3 Sheets-Sheet 2 WITNEssEs;/25 37 6 INVENTOR ferome/W50na//h TTORNEY Patented Apr, 1s, 1939 UNITEDSTATES PATENT OFFICE 2,154,703 n omoUrr rNTEaaUPTEa `lerome M. Sandin,Forest Hills, Pa., assignor to Westinghouse Electric & ManufacturingCompany, East Pittsburgh, Pa., a corporation of Pennsylvania ApplicationSeptember 12, 1935, Serial No. 40,194

` (ci. zoo-9s) 30 Claims.

sign has always presented a rather complexy problem to the art. Due tothe large amounts of available power which may be fed into the circuitupon the occurrence of fault conditions, it is necessary, to giveadequate protection to the controlled equipment, that the breakers shall15 be capable of interrupting large amounts of power within very shortintervals ,of time. Further, since the devices are ordinarily operatedby more or less inexperienced persons, it is imperative that they shallbe absolutely safe and 20 reliable in operation. 4 v

In order to prevent undesirable'discontinuities in service while at thesame time providing satisfactory protection of -the controlled circuitsand the connected equipment, it is necessary that 25 the' breakers shallbe capable of distinguishing between prolonged overl'oads and those of atransient nature. In addition, vit is necessary, in certaininstallations, that the equipment shall be -responsive to abnormalvoltage conditions and 30 that it may be actuated by remotely disposedcontrol means of the relay or other type.

In contrast with these operational require--v ments, it is absolutelyimperative that the physical vdimensions of these breakers shall be keptwithin certain deilned limits, in order to permit their use in existingpanelboard and other switch structures. In addition, it is necessarythat the initial cost of the breakers shall not be excessive, due tothe'large `numbers which 40 are used on even a small system or network,and it is desirable that the breakers shall be easy to service in orderto minimize maintenance costs. The provision of a breaker which iscapable of meeting all oi' these requirements con- 45 stitutestheprincipal object of the present invention. x w,

One form of breaker which has met with considerable success in the pastutilizes a single standardized contact structure and actuating mechanismfor arather wide range o;-r current values, the rating of any particularbreaker being vdetermined by the provision of a suitable trip'device.The closure for these breakers comprises a cooperating base and cover,preferably 55 formed of molded insulating material. By means 4extendsacross all of the poles thereof and is 10 of suitable ribs andpartitions in the multi-pole forms, a separate space or chamber isprovided for each ofthe poles. The movable contacts i'or the severalpoles are mechanically tied together so as to move as a unit,l and asingle operating mechanism, normally disposed in one of the pole spaces,is utilized for actuating all of the contacts.

The trip device for the multi-pole breakers adapted to engage and beretained within a suitable recess formed in the cooperating cover andbase. The device includes tripping means operable in response topredetermined electrical conditions in the circuit controlled by each of16 the poles of the breaker. By making the trip device readilyinterchangeable with other similarly proportioned device, it is possibleto market a whole line of breakers built up around the single,standardized, contact structure and actuating mechanism.

For most installations, it is necessary to provide but two trippingmeans for each of the poles of the breaker, one a thermally responsiveelement operable after a predetermined time delay upon the occurrence ofa prolonged moderate overload to effect the operation of the trip deviceand the other operable substantially instantaneously upon the occurrenceof predetermined large magnitude overloads. In other installations, itis also necessary to provide under-voltage A77tripping means, shunttripping means, and similar arrangements. The incorporation of auxiliarydevices of these latter types into the known forms of circuit breakerand trip devices through the utilization of the unoccupied portion ofthe pole chambers constitutes a further object of the present invention.

Another object of the invention consists in 'the provision of means forcooperating with the 40 .actuating mechanism for controlling theoperation of auxiliary tripping devices.

A further object of the invention is to provide a removable trip deviceinterchangeable with similar devices of like or diiferent rating forcontrolling the operation of circuit breakers which may be calibratedand sealed at the factory and to which, at the option of the user, maybe added additional tripping means or other auxiliary devices withoutnecessitatlngthe opening of the closure for the trio device, with theaccompanying danger that the calibration thereof might be changed.

A still further object of the invention is to provide an interchangeabletrip device of the type which includes a separate sealed closure for themovable portions thereof and which is removable as a unit fromcooperative engagement with the associated breaker mechanism withnon-adjustable tripping means adapted to operate in conjunction with thenormal tripping means of the breaker. Ihese additional tripping means tobe disposed without the closure of the trip device.

An ancillary object of the invention is to provide an improved shunt;trip element and an improved under-voltage trip element for a circuitbreaker trip structure of the type -under discussion, and to provide asimple means for controlling the operation of such devices in responseto the operation of the associated breaker actuating mechanism andcontact structure.

'I'hese and other objects will be ymade more apparent by reference tothe following drawings and descriptions of certain preferred embodimentsof the invention. Referring particularly to the drawings:

Figure 1 is a plan view of a three-pole circuit Ibreaker wherein areembodied the features of the invention. The cover of the breaker hasbeen almost completely cut away in order to more clearly illustrate thevarious structural elements.

Fig. 2 is an enlarged sectional view taken on the line II-II of Fig. 1.

Fig. 3 is a fragmentary View of the trip device and a portion of theoperating mechanism of the breaker illustrated more completely in Figs.1 and 2.

Fig. 4 is an enlarged sectional view, of the trip device shown in theother gures of the drawings. The view is taken on the line IV-IV of Fig.3.

Fig. 5 is an enlarged view of the shunt trip element forming a part ofthe trip device shown particularly in Figs. l'and 2.

Fig. 6 is a sectional view on the line VI-VI of Fig. 5.

Fig. 7 is a view corresponding to Fig. 6, showing the features of theunder-voltage trip element forming a part of the trip structure shownparticularly in Figs. l and 2.

Fig. 8 is an enlarged fragmentary view, partially in section, of theoperating linkage utilized in conjunction with the under-voltage tripelement,

. and

Fig. 9 is a fragmentary enlarged view of the trip bar and portions ofthe bimetallic thermally responsive trip elements forming a part of thetrip device proper. Y

The circuit breaker illustrated particularly in Figs. 1 and 2 is, asmentioned above, of the three pole type. The base I upon which all ofthe structural features of the breaker are mounted is formed of moldedinsulating material and is provided with suitable ribs or partitions 3formed integral therewith for separating the three poles. l

The cover 5 is likewise formed of molded insulating material and isprovided with cooperating ribs 1, as is shown particularly in Fig. 2,for engaging the similarly disposed ribs 3 in the base.

In the completed structure, these ribsl or parti-l tions 3 and 1 serveto dene three chambers which have the substantial form of rectangularprisms and which are spaced side by side.

Six terminals 9, three of which are affixed to either end of the base bymeans of suitable bolts II provide a means whereby the breaker may beconnected into an electrical circuit. The electrical circuit througheach of the poles of the breaker is substantially the same. A rigidstrap member I3 of conducting material, preferably copper, serves tosupport each of the stationary contact members I5 and to connect thosemembers with the adjacent cooperating terminal 9. A

movable contact member I1 pivotally supported.

formed of laminated material is electrically and mechanically connectedto the rear end of each of the movable contacts I1, and each oi theseilexible conductors 23 terminates in a solid terminal member 25 which isadapted to cooperate with one of the terminals 29 of the breaker tripdevice 21.

As is shown particularly in Figs. 1 and 2, the l trip device 21 isprovided with six of these terminals 29, two for each of the poles ofthe breaker. Each pair of the terminals 29 is electricallyinterconnected within the device itself by a looped conducting strip 3|,formed of laminated l material, which serves as an energized heater forthe thermally responsive trip element and as an energizing coil for themagnetically responsive trip element associated with each of the polesof the trip device. Each of the upper terminals "29 of the trip device21 is afiixed to one of the block terminal members 25 by means of a pairof screws 33 and each of the lower terminal members is in turn afxed toone of theterminals 9 oi the breaker by a pair of the bolts II. Thus,the conducting strip 3| interposed between each of the pairs ofterminals of the trip device serves to complete the electrical circuitfor each of the poles of the breaker from the terminal member 25 to thelower breaker terminal 9.

Each oi' the contact supporting frames I9 vis bolted to a square tiemember 35, comprising a steel core and an outer sheath of insulatingmaterial, in order to permit the simultaneous actuation of the contacts.A single operating mechanism 31 is/provided for simultaneously actuatingthe contacts.

The contact supporting frame I9 for the central pole has a link member39 cast integral therewith, and this link member is pivotally supportedupon the frame 4I of the actuating mechanism 31 by a suitable pivot pin43, the pin 43 thus serving to support the entire assemblage ofinterconnected movable contacts. 'I'he operating mechanism 31 ispreferably of the type disclosed in the copending application of HarryJ. Lingal, Serial No. 637,749, filed October 14, 1932, which becamePatent No. 2,083,305 on June 8, 1937 and which is assigned to theassignee oi' the present invention. As illustrated in Fig. 2, the

mechanism includes a pair of toggle links and 41, an operating member49, an over-center spring 5I intermediate the operating member and thetoggle links for causing those links to move from the normal closedcircuit position shown in Fig. 2 to a collapsed open circuit position,or vice versa, in response to movement of the operating member 49. Oneend oi the interconnected toggle links is supported upon a cradle member53 which is normally retained in the position shown in Fig. 2 by atrigger member 55 adapted to engage and cooperate with the trip device21. The trip device normally retains the trigger member 55 in theposition shown in Fig. 2, and when the trigger is in that position theactuating mechanism 31 is operable in response to movement of theoperating handle 49 to move the interconnected movable contacts |1 tothe open and to the closed circuit position.

Upon the actuation of the trip device, the trigger member 55 isreleased, and it moves aut'cmatically to a position where it causes theactuating mechanism 31 to eilect the opening of the breaker,independently of the position of the operating handle 49. By virtue ofthe overcenter spring construction, the contacts are at all times movedto the open, to the closed and to the tripped position, (which issubstantially the same as the open position) with a snap action.

'I'he various structural elements of the trip device 21 are mounteduponl a separate base member 51 which is adapted to engage a suitablerecess 59 formed withinr the cooperating base and cover which comprisethe breaker closure. The device includes a latch 5|, which is shownparticularly in Fig. 4 forengaging and retaining the trigger member 55of the breaker actuating mechanism in its normalr operative position, atrip bar 52 movable from a normal inoperative position to an operativeposition to release the latch 5| and effect the operation of the tn'pdevice, a plurality of thermally responsive, trip elements, each ofwhich is energized in response to the current ow in one of the poles ofthe breaker, and a plurality of magnetically responsive trip elementseach of which is likewise energized in response to the current flow inone of the poles of the breaker. of the thermally responsive tripelements and each of the magnetically responsive trip elements isindividually operable upon the occurrence of predetermined conditions tomove the trip bar 52 from the normal inoperative position, shown in Fig.4, to a position where it causes the latch member 5| to release thetrigger member 55 and thus effect the opening of the breaker. The tripbar 52 is pivotally supported at either oi' its ends upon suitablebracket members 55 ailixed to the base 51 of the trip device and extendsacross all three of the poles of the breaker. It is biased to its normalposition by a suitable spring 51 and since the latch 5| is also biasedto the normal latched position, the trip device is automatically prisesa tapered strip of bimetallic material 58 `which is supported at one endthereof upon a U-shaped frame member 59, the frame member being, inturn, bolted to the base 51 of the trip device. 'Ihe looped portion ofthe laminated conductor 3| disposed between each of the pairs ofterminals 29 of the trip device extends along 'the bimetallic member 58and is affixed to the lower end thereof and to the supporting U-,shapedframe 59 therefor by means of a pair of rivets 1|. The upwardlyextending portion of the bimetallic element 58 is provided with anadjustable screw 13 for engaging the trip bar 62.

Each of the magnetically responsive elements includes a U-shaped coremember I5 supported upon the adjacent U-shaped frame 89, and a slidablysupported armature 11 biased away from the cooperating core member 15 bya pair of springs 19. The core member is energized by current iiowthrough the associated looped conductor 3|, and the springs 19 are soadjusted that movement of the armature takes place only following theoccurrence of predetermined severe overload conditions. The trip bar 52is provided with three downwardly projecting members 8| one of which isdisposed in the normal path of Each movement of each of the armatures11, in order that movement of the armatures may be transmitted to thetrip bar. Thus, the trip bar may be moved from the normalinoperative tothe tripped or operative position by the bending of any one of thebimetallic elements 58 or by the movement of y any one of the slidablearmatures 11 from the unattracted to the attracted position.- A supportbracket 83 is rigidly afllxed to the base 51 of the trip deviceat thecentral portion thereof, and this bracket is provided with a pin 84adapted to engage a suitable recess 85 formed in the block terminal ofthe central pole in order to accurately position the4 trip device 21with respect to the other features of the breaker mechanism. Thisbracket 83 also serves to support and accurately position the trip latch5|.

A removable cover 85, formed o'f molded insulating material, is providedfor enclosing the various structural features ,l of the trip device.This cover is normally supported upon the brackyets 55 by means ofsuitable screws 81 and these screws are preferably sealed in position bya seal 88 as is shown in Fig. 3, during the manufacture of the device,in order to prevent unauthorized persons from tampering with thecalibration of the trip elements.

In addition to the above-mentioned thermally responsive and magneticallyresponsive trip elements, the device shown in the drawings is furtherprovided with a shunt trip element 9| and an under-voltage trip element93. Each of these elements is supported upon the base 51 of the tripdevice by means of a, suitable bracket member 95 and a pair of bolts 91,and each is readily removable therefrom without necessitating theremoval of the cover 85 of the trip device. The bracket members '95 areso arranged that they support the under-voltage and the shunt tripelements a substantial distance away from the base 51 of the trip deviceand thereby assure that theaddition of either or both of these elementsshall in no way interfere with the removal or replacement of the tripdevice by` preventing free access to the removable screws 33 utilizedfor connecting the trip device into the breaker structure.

'Ihe shunt trip element 9| is shown particu--l larly in Figs. 5 and 6.It includes a 4U-shaped core |8| of magnetic material rigidly amxed to,

' or formed integral with, the supporting bracket 95. An iron pole piece|83 is screwed into a suitable recess formed in the outer end of thisUfshaped core |8|, and a brass tube |85 which serves as a guide vfor themovable armature 81 of the element engages a suitable supportingshoulder formed in this pole piece. The inner end of the brass tube |85is retained in position -Y by a cap member |89 which serves the furtherfunction of providing a stop for the armature. The armature |81 iscylindrical in form and is provided with a hollow cylindrical recessformed in the outer end thereof for positioning a suitable biasingspring Ill. The coil means 3 for energizing the pole piece of the deviceis disposed about the brass tube |85 and is insulated from metallicportions of the device by an insulating spool'li 5. A tie-rod ||1,preferably of insulating material, is aillxed to the inner end of thearmature |81 and is provided with a C- shaped member ||8 for engagingone of the projections i9 forming a part of the trip bar 52. This rodand the C-shaped trip bar engaging member ||8 move within a suitablehole |2| formed within the base 51 of the trip device. The

-oi strap conductors |21 disposed within suitable recesses formedtherein, and a third strap member |29 for -bridging the members |21. Thebridging member |29 is supported for movement into and out of bridgingengagement with the straps |21 by means of a slidable rod member |3| oi'insulating material having a head |33 formed integral therewith. Thisinsulating support memfber |3| is biased to the closed circuit orbridging position by means of a spring |35 and is adapted to be moved soas to open the electrical circuit through the switch by the engagementof an L-shaped member |31 ailixed to the contact supporting frame I9 forthe outer pole. Through this arrangement, the electrical circuit throughthe energizing coil I3 for the shunt trip element 9| is opened at twopoints, immediately upon the movement of the breaker contacts to theopen circuit position, and any danger of the coil being burned out isthereby eliminated.

The under-voltage trip element 93 is shown particularly in Fig. 7.Similar to the shunt trip element 9|, it includes a U-shaped frame 20|of magnetic material formed integral with the supporting bracket 95therefor. The pole piece 203 is threaded into the inner side of theU-shaped frame 20|, as contrasted with the pole piece |03, due to thediil'erence in the direction of movement of the armatures. The armature201 is cylindrical in form, is provided with a suitable biasing spring2|4 for directing it away from the pole piece 203, and-is adapted tomove within a brass tube 205 ordinarily retained in abutting engagementwith a shoulder formed in the pole piece. by an outer cap member 209.The amature 201 includes an inwardly extending rod 2|l adapted tooperatively engage the tie rod |I1 and the C-shaped member ||9 whichcomprise the trip bar engaging means, substantially the same as for theshunt trip element. A suitable voltage responsive energizing coil 2|3serves to retain the armature 201 in the position shown in Fig. 7 exceptwhen the energizing voltage falls below a predetermined minimum value.

In order to assure that the Yarmature of the under-voltage element shallbe moved into contact with the cooperating pole piece following eachoperation of the breaker, a mechanical linkage means is provided forinterconnecting the armature with the breaker contact assemblage. Thislinkage includes a rigid metallic member 22| aixed to the supportingframe |9 for the right-hand movable contact member, an insulating link223, and a spring plunger means ailixed to the armature 201 itself. 'Iheplunger means comprises a rod member having an enlarged outer portion229 and an inner portion 23| of reduced area upon which a washer 233 isadapted to slide, this washer being normally biased against the shoulderformed by the enlarged outer end 229 by'a suitable spring 235. Theintermediate link 223 has a cylindrical guide opening 231 of somewhatlargerdiarneter than ythe outer end 223 to assure the movement of therod member therein, and when the contacts move to the open circuitposition, this intermediate member engages the slidable washer 233 andmoves that washer to a position where the stress transmitted through thespring 235 is suillcient torestore the armature 201 to its normalposition. In this position the impedance of the device reaches itsmaximum value and burning out of its energizing coil 2|3 upon therestoration of voltage to the energizing circuit is prevented.

The operation of the trip device 21 is believed to be more or lessobvious from the foregoing. Upon the occurrence of a predetermined lowmagnitude overload in the circuit controlled by any one of the poles ofthe breaker and the persistence of that overload for a predeterminedperiod of time, the bimetallic element 6l, energized in response to thecurrent flow in that pole, is caused to bend and move the trip bar 62 tothe operative position. In this position the latch 5| no longerrestrains the trigger member 55 in the position shown in Fig. 2 and thetrigger member moves automatically to cause the actuating mechanism 31to eiect the opening of the breaker irrespective.of the position of theoperating handle 49. Similarly, upon the occurrence of a predeterminedlarge magnitude overload in the circuit controlled by any one of thepoles oi' the breaker, the associated core member 15 is energizedsufliciently to attract the cooperating armature 11 and thereby move thetrip bar 62 from the normal inoperative to the tripped position.

The thermally responsive and the magnetically responsive trip elementsprovide complete overload protection for the circuits controlled by thebreaker, but they do not give protection against under-voltage orover-voltage conditions nor do they permit remote control of thebreaker. These latter functions are accomplished by the shunt tripelement 9| and the under-voltage trip element 93. In the shunt tripelement the armature is moved magnetically, in the under-voltage elementthe armature is restrained from movement by an electromagnetic field.Together the elments provide a exible arrangement capable ot meeting allpossible requirements.

Both elements may be added to a trip device of the type disclosed in thesubject application without ,necessitating the removal of the cover ofthat device. Factory adjustments and calibrations are thus preservedthroughout the operative life of the device. In both elements thearmature engages the trip bar only during the latter portion of itsmovement from the inoperative to the operative position. 'I'his assurespositive actuation of the trip bar by permitting the armature to acquiresubstantial kinetic energy before engaging and moving that member.

The lead terminals 25| of the shunt and undervoltage trip elements arepreferably brought out of the breaker closure through suitable holes 253formed in the side walls of the base member From the foregoing, it willbe seen that I have disclosed the features of a new and improved form ofelectro-responsive trip device, particularly suitable for use withcircuit breakers of the type which employ standard operating mechanismsand interchangeable trip structures. In addition, I have disclosedauxiliary tripping means such as under-voltage and shunt trip deviceswhich may be added to known forms of tripv structures withoutnecessitating the removal ol' thecovers of those devices or withoutneces sitating any substantial alteration in the associated equipment.'

In the preferred form of my invention, I so position these auxiliarytripping means on the base of the trip device that they extend into thespace ordinarily left unoccupied when the breaker is in operation, thatis, within the excess space in the chambers provided for each of thepoles.` This probably is one of the most important features of thepresent invention because it is only by this novel arrangement that theuse of these auxiliaries in conjunction with existing equipment is madepossible.y

It will immediately be obvious that my provision loi' auxiliary controlmeans for'tripping devices and my improved arrangement of the structuralfeatures of these devices has effected a substantial extension of theuseful range of operation of these devices without any accompanyingdeleterious effects whatsoever. 'I'he resultant trip devices are stillreadily interchangeable, and their normal operational qualities are inno way effected by the addition of the auxiliary means in accordancewith the invention.

Further, I have disclosed certain preferred structural arrangements foraccomplishing the other objects ofy the invention, and I have shown howthe operation of my improved under-voltage and shunt trip device may becontrolled by the operating mechanism and the contacts of the breaker.

While in accordance with the patent statutes, I have, in the foregoing,disclosed the features of certain preferred structural arrangements andembodiments of my invention, it is to be understood that thesestructures are merely illustrative. Variations in their precise form mayand probably will be not only desirable but necessary in many instanceswithout departing from the concept of the invention and it is my desire,therefore, that the language of the accompanying claims shall beaccorded the broadest reasonable construction and shall be limited onlyby what is expressed therein and by the prior art.

I claim as my invention:

1. In a circuit interrupter, separable contact means for opening and forclosing the electrical circuit therethrough, actuating means for saidcontact means, a trip device operable upon the occurrence ofpredetermined conditions to cause said actuating means to move saidcontact means automatically to the open circuit position, said tripdevice being removable from said interrupter as a unit and including abase, a cover which cooperates with said base to define a closure forsaid device, electro-responsive tripping` means disposed within saidclosure. and other electroresponsive tripping means supported on saidbase outside said closure, said last mentioned means y, being removablefrom operative engagement with said trip device without necessitatingthe removal of said cover. and means for mechanically interconnectingsaid last mentioned tripping means with said separable contact means andthe actu-` ating means therefor.

2. In a circuit interrupter; separable contacty means for opening andfor closing the .electrical circuit therethrough; actuating means` forsaid I contact means; and a trip device operable upon said closure, andauxiliary tripping means disposed outside said closure; said lastmentioned means being readily removable from operative engagement withsaid trip device without necessitating the opening of said sealedclosure, to permit similar means of like or different characteristics tobe substituted therefor.

3. A trip device for a circuit interrupter comprising a unitarystructure removable as a unit from said interrupter and including abase, a cover for cooperating with said base to define a closure forsaid device, terminals mounted on said base for releasably connectingsaid device into the electrical circuit or circuits controlled by theassociated interrupter, electro-responsive tripping means disposedwithin said closure, and auxiliary electro-responsive tripping meanssupported on said base outside said closure, said last mentionedtripping means being readily removable from and movable into operativeengagement with said trip device without necessitating the removalofsaid cover, to permit similar means of like or differentcharacteristics to be substituted therefor.

4. A trip device for a circuit interrupter comprising a unitarystructure removable as a unit from said interrupter and including abase, a cover for cooperating with said base to define a. closureforksaid device, terminals mounted on said base for releasablyconnecting said device into the electrical circuit or circuitscontrolled by the associated interrupter, electro-responsive trippingmeans disposed within said closure, and at least two auxiliaryelectro-responsive tripping means supported on said base outside saidclosure, one of said auxiliary tripping means including an armaturebiased to an operative position and electro-magnetic means forrestraining said armature is an inoperative position, another of saidauxiliary tripping means including an armature biased to an inoperativeposition and electromagnetic means for moving said armature to anoperative position, said auxiliary tripping means being interchangeablewith each other and being removable from operative engagement with saidtrip device without necessitating the removal of said cover to permitsimilar means of like or different characteristics to be substitutedtherefor.

5. In a circuit interrupter; separable contact means for opening and forclosing the electrical circuit therethrough; actuating meansfor said'contact means; a trip device operable upon the occurrence ofpredetermined conditions to cause said actuating means to move saidcontact means automatically to the open circuit position; said tripdevice being removable from said interrupter as a unit and including asealed closure, electroresponsive tripping means disposed within saidclosure, and at least two auxiliary electro-responsive tripping meansdisposed outside said closure; one of said auxiliary tripping meansincluding an armature biased to an operative position andelectro-magnetic means for retaining said armature in an inoperativeposition; another of said auxiliary tripping means including an armaturebiased to an inoperative position, a current-carrying attracting coilfor moving said armature to an operative position, and a switching meanselectrically connected in series with the circuit through saidattracting coil; said auxiliary tripping means being interchangeable.with each other and being 'removable from operative engagement withsaidtrip device without necessitating the opening of said closure, topermit similar means oi' like or different characteristics to besubstituted therefor; and means for mechanicallyinterconnecting saidauxiliary tripping means with said contact means and said contactactuatingmeans, in order that the amature of said first mentionedauxiliary tripping means shall be restored to said inoperative positionin response to each openingmovement oi said contact means resulting frommovement of that armature to said operative position, and in order thatthe operation of said switching means forming a part of said lastmentioned tripping means shall be caused to take place in response tomovement of said contact means.

6. Ina multi-pole circuit interrupter; a base; a cover for cooperatingtherewith to define a closure for said interrupter; conducting meansincluding a plurality of pairs of separable contacts for defining theplurality of poles of said `interrupter; means for dividing said closureinto a plurality of separate chambers, one for each of said poles; theconducting means for each of said poles being ydisposed in one oi' saidchambers; a single actuating means for a plurality of said pairs orseparable contacts, said actuating means being disposed within one ofsaid pole chambers;y

and a trip device operable\to cause said contact actuating means to movesaid plurality of pairs of separable contacts automatically to the opencircuit position, said trip device being disposed within said .closurefor said interrupter and removable from said closure as a unit, saidunit including a separate closure, electro-responsive tripping meansdisposed 'within said separate closure, and other electro-responsivetripping means disposed without said separate closure; said lastmentioned tripping means being readily removable from operativeengagement with said trip device, without necessitating the opening ofsaid separate closure, to permit similar means of like or dierentcharacteristics to be substituted therefor, and being adapted to extendinto one or more of said chambers when said trip, device is in thenormal operative position within said'main closure.

7. In a multi-pole circuit interrupter; a base; a cover for cooperatingtherewith to define a closure for said interrupter; conducting meansincluding a plurality oi pairs ,of separable 'con--v tacts for definingthe plurality of lpoles of said interrupter; cooperating partition orrib members formed integral with said base and said cover for dividingsaid closure into a plurality of separate chambers, one for each of saidpoles; the conducting means for each of said poles being disposed in oneo1' said chambers; a single actuating mechanism for said plurality ofpairs of separable contacts, said actuating mechanisml being disposedwithin one of said pole chambers; and a trip device operable to causesaid contact actuating means to move said plurality of pairs ofseparable contacts automatically to the open circuit position, said tripdevice being disposed in a suitable recess'iormed Within said closurefor said interrupter and removable therefrom as a unit, said unitincluding a separate, sealed closure adapted to extend across said polechambers adjacent one of the ends thereof, electro-responsive trippingmeans disposed within said sealed closure, and auxiliary tripping meansdisposed without said sealed closure; said auxiliary tripping meansbeing readily removable from operative engagement with said trip device,without necessitating the opening of said sealed closure, to permitsimilar means of like or diierent characteristics to be substitutedtherefor and being adapted to exf tend into one or more ci said polechambers when said trip device is in the normal operative positionwithin said closure for said interrupter.

8. In a multi-pole circuit interrupter; a base;

a cover for cooperating therewith to detine a closure for saidinterrupter; conducting means including a plurality of pairs ofseparable contacts for dening the plurality oi.' poles of saidinterrupter; cooperating partition or rib members formed integral withsaid base and said cover -for dividing said closure into a plurality ofseparate chambers, one for each of said poles; the conducting means foreach of said poles being disposed in one of said chambers; a singleactuating mechanism for said plurality oi' pairs of separable contacts,said actuatingv mechanism being disposed within one oi said polechambers; a trip device operable to cause said contact actuating meansto move said plurality of pairs oi separable contacts automatically tothe open circuit position, said trip device being disposed in a suitablerecess formed within said closure for said interrupter andremovabletherefrom as a unit. said unit including a separate closureadapted to extend across said pole chambers adjacent one oi the endsthereof, electro-responsive tripping means disposed within said closure,and auxiliary tripping means disposed without said closure; saidauxiliary tripping means being adapted to extend into one or more ofsaid pole chambers when said trip device is in the normal operativeposition within said closure for said interrupter; and means formechanically connecting said auxiliary tripping means with saidseparable contacts and said contact actuating means, saidconnectingmeans including means movable in one or more of said polechambers. n

'9. In a circuit interrupter, separable contact means for opening andfor closing the electrical circuit therethrough, actuating means forsaid contactmeans, a trip devicey operable upon the occurrence ofpredetermined conditions to cause saidactuating means to move saidcontacts automatically to the open circuit position, said trip devicebeing removable from said interrupteras a unit and including a base, acover which cooperates with said base to deiine a closure for said tripdevice, electro-responsive tripping means disposed within said closure,and other electro-retripping means inoperative when the contacts are inthe open position.

10. In a circuit interrupter;4 separable contact means for opening andfor closing the electrical circuit therethrough; actuating means forsaid contact means; a trip device mounted at one end of said actuatingmeans and operable to cause said actuating means to move said contactmeans automatically to the open circuit position; said trip device beingremovable as a unit from operative engagement with the other elements ofsaid interrupter and including a base, a cover which cooperates withsaid base to define a closure for' said trip device, current-carryingelectro-responsive tripping means disposed within said closure, andother current-carrying electro-responsive tripping means disposedoutside said closure and beside saidy actuating means intermediate saidtrip device and said separable contact means, and

an auxiliary switching means disposed without said closure and besidesaid actuating means intermediate said trip device and said separablecontact means, said auxiliary switching means being electricallyconnected in series with the circuit through one of saidcurrent-carrying tripping means; and means for effecting the actuationof said auxiliary switching means in response to the opening and theclosing movement of said contact and said contact actuating means.

11. In a circuit interrupter; separable contact means for opening andfor closing the electrical circuit therethrough; actuating means forsaid contact means; a trip device operable to cause said actuating meansto move said contact means automatically to the open circuit position;said trip device being removable as a unit from operative engagementwith the other elements of said interrupter and including anelectro-magnetic tripping means which comprises an armature movable.from a normal inoperative to an operative positionu to effect theoperationv of said trip device; and resilient connecting means connectedbetween said contact means and the aforesaid armature to permit lostmotion between said contact means and said armature and operable, whensaid contact means is moved to the open circuit position in response toan operation of said trip device caused by movement of said armature tosaid operative position, to return said armature to said inoperativeposition.

12. In a circuit interrupter; separable contact means for opening andior closing the electrical circuit therethrough; actuating means forsaid contact means; a trip device operable tocause said actuating meansto move said contact means automatically to the open circuit position;said trip device being removable as a unit from operative engagementwith the other elements of said interrupter and including an armaturemovable from a normal inoperative to an operative position to effect theoperation of said trip device, means biasing said armature to saidoperative position,'and electro-magnetic means for holding said armaturein said inoperative position against the force of said biasing means;said electromagnetic vmeans permitting said` biasing means to movi.lsaid armature to said operative position following the occurrence ofpredetermined conditions; and resilient means mechanicallyinterconnecting said movable armature with said contact and said contactactuating means, said resilient means causing said amature to bereturned to said inoperative position following each operation of saidtrip device resulting from movement thereof and permitting said contactand said contact operating mea-ns to continue movement after saidarmature has reached said inoperative position.

13. In a circuit breaker having separable contact members, actuatingmeans for operating said contact members to open and closed positionsand tripping means for causing said actuating means to operate saidcontact members to the open position upon the occurrence ofpredetermined conditions, said tripping means comprising the combinationwith a sealed calibrated trip device removable as a unit from saidbreaker of an auxiliary trip actuating means, said auxiliary tripactuating means being removable from and replaceable in operativeengagement with said trip device without disturbing the seal of thelatter.

14. In a circuit breaker having separable contact members, actuatingmeans for operating said contact members to open and closed positionsand tripping means for causing said actuating means to operate saidcontact members to the open position upon the occurrence ofpredetermined conditions, said tripping means comprising the combinationwith a sealed calibrated trip `device removable'as a unit from saidbreaker of 'an aux iliary current-responsive trip actuating element,said element being removable from and replaceable in operative'relationwith said trip device without disturbing the calibration of the latter,switching means incircuit with said auxiliary current-responsive tripactuating element, and means operable upon the movement of said contactmembers for actuating said switching means.

15. In a circuit breaker having separable contact members, actuatingmeans for operating said contact members to open and closed positionsand tripping means for causing said actuating means to operate saidcontact members to the open position upon the occurrence ofpredetermined conditions, said tripping means comprising the combinationwith a sealed calibrated trip device removable as avunit from saidbreaker of an auxiliary current-responsive trip actuating element, saidelement being removable from and replaceable in operative relation4 withsaid trip device without disturbing the calibration of the latter,switching means. in circuit with said auxiliary current-responsive tripactuating element, and control means adapted to be actuated by saidactuating means for said contact members for operating said switch meansto deenergize said auxiliary current-responsive trip actuating elementwhen-said contact members are in the open' position. i

16. In a circuit breaker having separable contact members, actuatingmeans for operating said contact members to open and closed positionsand tripping means for causing said actuating means to operate saidcontact members to the open position upon the occurrence ofpredetermined conditions, said tripping means comprising the combinationwith a sealed calibrated trip device removable as a unit from saidbreaker of an auxiliary current-responsive trip actuating element, saidelement being removable from and replaceable in operative engagementwith said trip device without disturbing the seal of the latter, andmeans actuated by said actuating means for said AContact members forrendering said auxiliary current-responsive trip actuating. elementinoperative when said contact members are in the open position.

17. The combination with a trip device for a multi-pole circuit breaker,said trip device being removable from said breaker as a unit andincluding a trip bar which is movable for causing the automaticoperation of the circuit breaker contacts to the open position and acalibrated current-responsive element for each pole adapted to actuatesaid trip bar upon the occurrence of predetermined conditions of one-ormore auxiliary current-responsive elements operable upon theoccurrenceof other predetermined conditions to actuate said trip bar,said auxiliary current-responsive elements being removable from andreplaceable in operative relation with saidtrip device withoutdisturbing the calibration of said first-named current-responsiveelements.

18. The combination with a trip device for a multi-pole circuit breaker,said trip device being removable from saidv breaker as a unit andincluding a trip bar normally biased to a latching position forretaining the circuit breaker contact operating mechanism in the closedposition and a calibrated movable current-responsive element for eachpole, said trip bar having a projection for each pole adapted foroperative engagement with a current-responsive element for movementthereby to the tripped position upon the occurrence of predeterminedconditions oi' one or more auxiliary current-responsive elementsoperable upon the occurrence `-of other predetermined conditions, saidauxiliary current- 1 responsive elements having means operativelyengaging at least one of said projections to actuate said trip bar tothe tripped position independently of said calibrated current responsiveelements, said auxiliary current-responsive elements beu ing releasablefrom and replaceable in operative relation with said trip device withoutdisturbing the calibration of said first-named current-responsiveelements. l 19. In a circuit interrupter, actuating means m for openingand closing the circuit interrupter, an under-voltage trip deviceoperable to cause said actuating means to open the circuit interrupterupon the occurrence of a predetermined under-voltage condition, saidtrip device includu ing a member biased to move to tripped position andcurrent-responsive means normally holding said memberv and releasing itupon the occurrence of said predetermined under-voltage condition, andconnecting means including a' resilient member positioned between saidactuating means and said biased member and through which movement ofsaid actuating means is transmitted to said biased member for returningit to position where it is heid by the current-responsive means, saidresilient member permitting greater movement of said actuating meansthan is required to return said biased member into operative relationwith said holding means.

20. In a circuit interrupter, a base member, o separable contact meansfor opening and closing the circuit through the circuit interrupterpositioned on the base member adjacent one end thereof, actuating meansfor the contact means positioned directly against the base member adajacent the mid-portion thereof, a trip unit including current-responsivemeans positioned on the base member adjacent the other end thereof,v

an auxiliary trip devic'e'positioned in the space beside said actuatingmeans and between said o trip unit and said contact means, connectingmeans extending from said auxiliary trip device to said trip unit foractuating the trip unit upon operation of the auxiliary trip device, andmeans movable upon the operation of said actuating u means to act onsaid auxiliary trip device.

21. In a circuit interrupter, a base member, separable contact means foropening and closing the circuit through the circuit interrupterpositioned on the base member adjacent one end y thereof, actuatingmeans for the contact means positioned close to the base member adjacentthe mid-portion thereof, a trip unit including current-responsive meanspositioned on the base member adjacent the other end thereof, anunder-voltage trip device positioned in the space beside said actuatingmeans and between Said trip unit and said contact means, saidundervoltage trip device including a coil and an armature biased to moveto tripped position, an oper- 7 ating connection extending from saidunder-voltage trip device to said trip unit for actuating the trip unitupon movement of the armature to tripped position, and means movableupon the operation of said actuating means for engaging and resettingtheundervoltage trip device after each movement oi the armature totripped position.

22. In a circuit interrupter, a base member, separable contact means foropening and closing the circuit through the circuit interrupterpositioned on the base member adjacent one end thereof, actuating meansfor the contact means positioned close to the base member adjacent themid-portion' thereof; a trip unit including current-responsive meanspositioned on the base member adjacent the other end thereof, a shunttrip device including a coil, an armature movable by the coil and acut-oil' switch in series with the coil, all positioned in the spacebeside said actuating means and between said trip unit and said' contactmeans, an operating connection extending from said shunt trip device tosaid trip unit for actuating the trip unit upon movement of saidarmature, and means movable upon the operationof said actuating meansfor operating said cut-oli switch after each operation ot the shunt tripdevice.

23. In a circuit interrupter, separable contact means, actuating meansfor causing said contact means to open and close the circuit, a tripunit including electro-responsive means operable to cause said actuatingmeans to open the circuit. a housing enclosing said trip unit, anauxiliary trip device including a second electro-responsive meansmountedoutside of said housing, an opening in said housing, connectingmeans extending from said auxiliary trip device through said opening toactuate7 said trip unit by said second electro-responsive means, andsaid auxiliary trip device with said connecting means being removablefrom' and replaceable in operative relation with said trip unit throughsaid opening without opening said housing.

24. In a circuit interrupter, separable contact means for opening andclosing the circuit, a `mechanism for operating said contact means, ashunt trip device tor causing the actuation of said operating means,said shunt trip device including an electro-magnet and a cut-oil' switchtherefor mounted together to form a single unit, said shunt trip deviceincluding the electro-magnet and the cut-oil.' switch being removablefrom and replaceable on the circuit interrupter as a unit, and meansmovable with said operating mechanism for actuating said cut-oil switchwhen said operating mechanism has been caused to operate by the shunttrip device.

.- 25. In a removable shunt trip unit for a circuit breaker, anelectro-magnetic device includ- A ing a coil, an amature movable by thecoil, and a'spring opposing said movement of the armature by the cou, acut-on switch mounted on, said electro-magnetic device to i'orm. aunitary structure therewith and including contacts connected in serieswith said coil, circuit brekerv operating means extending from thearmature for engaging and operating the circuit breaker, and-anoperating member for the cut-oi! switch engageable andmovable by thecircuit breaker.

26. In an under-voltage trip unit for a circuit breaker, a solenoidhaving an opening therethrough, an armature movable in said opening butnormally held by the solenoid, biasing means for moving said armaturewhen released by the solenoid, circuit breaker operating means extendingfrom one end of said opening for engaging and operating the circuitbreaker upon movement of the armature, and resetting means for returningsaid armature against said biasing means into position where it may beheld by said of the armature, and resetting means for returning said'armature against said'biasing means intoposition where it may be heldby said solenoid, said resetting means having a portion extending fromthe other end of said opening and being engageable and movable by thecircuit breaker, and said resetting means including a member movable bythe circuit breaker and a resilient connection between said member andvthe armature permitting said member to be moved by the circuit breaker adistance greater than the armature may be moved.

28. In a multi-pole circuit interrupter, a base member, a line terminalmember for each of the poles of the circuit interrupter, said lineterminal members being positioned at intervals across one end of saidbase, a second line terminal member for each of the poles of the circuitinterrupter, said second line terminal members being positioned atintervals across the other end of said base, a plurality of separablecontacts positioned at intervals across said base adjacent the lineterminal members at one end of the base, a main trip device includingcurrent responsive tripping means for a plurality of said polespositioned at intervals across said base adjacent the line terminalmembers at the other end of said base, an actuating mechanism for saidseparable contacts positioned on said base intermediate said pluralityof contacts and said main trip device, said actuating mechanism being ofless width than the width of said main trip device and of less widththan the width of said plurality of contacts, an auxiliary trip devicepositioned in the space beside said actuating mechanism and intermediatesaid plurality of contacts and said main trip device, and connectingmeans extending from said auxiliary trip device to said main trip devicefor actuating said main trip device upon operation of the auxiliary tripdevice.

29. In a multi-pole circuit interrupter, a base member, a line terminalmember for each of the poles of the circuit interrupter, said lineterminal members being positionedat intervals across one end of saidbase, a second line terminal member for each of the poles of the circuitinterrupter, said second line terminal members being positioned atintervals across the other end of said base, a plurality of separablecontacts positioned atl intervals across said base adjacent the lineterminal members at one end oi' the base, a

ture main trip device including current responsive tripping means for aplurality of said poles positioned at intervals across said baseadjacent the line terminal members at the other end of said base, anactuating mechanism for said separable contacts positioned on said baseintermediate said plurality of contacts and said main trip device, saidactuating mechanism being of less width than the Width of said main tripdevice and of less width than the width of'said plurality of contacts.and under-voltage trip device positioned in the space beside saidactuating mechanism and between said plurality of contacts and said maintrip device, said under-voltage trip device including a coil and anarmature biased to move to tripped position, an operating connectionextending from said under-voltage trip device to said main trip devicefor actuating said main trip device upon movement of said armature totripped position, and means movable upon operation of said actuatingmechanism for resetting the under-voltage trip device after eachmovement of the armature to tripped position.

30. In a multi-pole circuit interrupter, a base member, a line terminalmember for each .of the poles of the circuit interrupter, said lineterminal members being positioned at intervals across one end of saidbase, a second line terminal member for each of the poles of the circuitinterrupter, said second line terminal members being positioned atintervals across the other end of said base, a plurality oi' separablecontacts positioned atl intervals across said base adjacent the lineterminal members at one end of the base, a main trip device includingcurrent responsive tripping means for a plurality of said ,polespositioned at intervals across said base adjacent the line terminalmembers at the other end of said base, an actuating mechanism for saidseparable contacts positioned on said base intermediate said pluralityof contacts and said main trip device, said actuating mechanism being ofless width than the width of said main trip device and of less widththan the width oi' said plurality of contacts, a shunt trip deviceincluding a coil and an armature movable thereby positioned in the spacebeside said actuating mechanism and between said plurality of contactsand said main trip device, an operating connection extending from saidshunt trip device to said main trip device for actuating said main tripdevice upon movement of said armato tripped position, a cut-off switchconnected in series with said coil and positioned in the space besidesaid actuating mechanism and between said plurality of contacts and saidmain trip device, and means movable upon the operation oi said actuatingmechanism for operating said cut-oir switch after each operation of theshunt trip device.

JEROME M. SANDIN.

